Contamination-resistant sand control apparatus and method for preventing contamination of sand control devices

ABSTRACT

The present invention relates to a contamination-resistant sand control apparatus and a method for preventing the contamination of sand control devices. More particularly, the invention involves placing time-release treatment chemicals in a flow channel that communicates with the sand control device. The treatment chemicals take the form of time-release capsules or are coated on a surface of the sand control device and may include scale inhibitors, paraffin inhibitors, asphaltene inhibitors, enzymes and the like. The treatment chemicals prevent and clear the formation and buildup of particulates on a surface of the sand control apparatus.

BACKGROUND OF THE INVENTION

The present invention relates to a contamination-resistant sand control apparatus and a method for preventing the contamination of sand control devices. More particularly, the present invention relates to an apparatus that controls sand flow and inhibits the formation and buildup of particulates on a surface of the sand control apparatus and a method for inhibiting the formation and buildup of particulates on a sand control device.

To prevent an influx of sand into production tubing, sand control devices, such as sand screens attached to the production tubing at desired production levels, are used to allow the flow of hydrocarbons and other fluids to proceed while preventing the flow of sand into the production tubing. A major problem that arises during fluid flow through the sand control devices, however, is the formation and buildup of unwanted materials on the surface of the sand control device as a result of substances found in the well fluids. Particulates of calcium carbonate, paraffin, and asphaltene, found in subterranean water, oil, and drilling fluids, can precipitate on the sand control device and impede hydrocarbon flow through the production tubing. Therefore, the removal and prevention of unwanted buildup and precipitation on sand control devices can be helpful and necessary to assure the uninhibited flow of hydrocarbons in the production tubing.

Current solutions to resist particulate buildup require that well production be shut down so that treatment chemicals can be pumped down the well. This process requires the treatment chemicals to soak into the well formation for two to three days, further suspending hydrocarbon production. In the event that particulate buildup has prohibitively blocked hydrocarbon flow, the sand control device needs to be decontaminated or cleaned of the blockage. Current solutions to decontaminate sand control devices involve pumping a corrosive fluid down the production tubing to dissolve any particulate buildup on the sand control device. These solutions, however, require that hydrocarbon production be shut down for two to three days and also require a workover of the production screen assembly. Furthermore, by the nature of pumping fluids into porous and permeable media, the accuracy of placement of treatments for contaminate removal is not perfect nor necessarily accurate.

Current preventative and decontamination measures must also be repeated approximately two times per year to resist restriction and clear flow into the sand control device. Therefore, current solutions are extremely expensive, time consuming, and resource intensive.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for preventing the contamination of sand control devices, which meet the needs described above and overcome the deficiencies of the prior art.

In one embodiment, the present invention is directed to a method for preventing the contamination of sand control devices. The method involves placing time-release treatment chemicals in a flow channel that communicates with a surface of the sand control device.

In another embodiment, the present invention is directed to an apparatus wherein chemical inhibitors are placed in a flow channel by disposing them within, or adhering them to, the sand control device before the sand control device is placed into a production zone. Chemical inhibitors are known in the art and the type or types used is largely dependent on the contaminants (e.g., scale, paraffins, and asphaltene) present in the well. Preferably, a single or some combination of scale inhibitors, paraffin inhibitors, and asphaltene inhibitors are used. In another aspect of the present invention, other treatment chemicals such as enzymes, which break down and eliminate organic-based drilling muds and completion fluid may also be used.

In addition, a preferred embodiment for this method uses encapsulated chemistry. In one embodiment, the encapsulated time-release treatment chemicals are approximately 1 to 5 millimeters in size and placed inside of a prepacked screen. In another embodiment, the time-release treatment chemicals are coated onto the inner and outer surfaces of the sand screen.

Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is better understood by reading the following description of non-limitative embodiments with reference to the attached drawings, which are briefly described as follows:

FIG. 1 is a diagram of a production screen assembly set in a gravel pack containing encapsulated time-release treatment chemicals;

FIG. 2 is a schematic diagram of a sand control screen wherein time-release treatment chemicals are coated onto a surface of the sand control screen; and

FIG. 3 is a schematic diagram of a sand control pre-pack wherein time-release treatment chemicals are disposed within the sand control device.

It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The details of the present invention will now be discussed with reference to the figures.

FIG. 1 shows a diagram of a sand screen 10 in accordance with the present invention, which has been inserted into a casing string 20 within a well bore 30 formed within a subterranean formation 1. The sand screen 10 is attached to a production tubing 40. The annulus between the sand screen 10 and casing string 20 is packed with gravel 50. A plurality of time-release treatment chemicals 60 are placed within the gravel pack 50 in accordance with one embodiment of the present invention. As those of ordinary skill in the art will appreciate, although FIG. 1 illustrates the sand screen 10 inserted into a casing string 20, it can alternatively be inserted into an open well bore.

Preferably, the time-release treatment chemicals 60 are encapsulated and include any combination of one or more scale inhibitors, paraffin inhibitors, asphaltene inhibitors, breaker chemicals and the like. The scale inhibitors preferably include any combination of one or more phosphates and organic esters. The paraffin inhibitors preferably include any combination of one or more heavy aromatic naphtha, hapthenic distillates, C-20-C-28 Olefins and Trimethylbenzene. The asphaltene inhibitors preferably comprise Targon, commerically known as N-Tyrol. The breaker chemicals include enzymes. As hydrocarbons and other drilling fluids flow from subterranean formation 1 through the gravel pack 50 and encapsulated treatment chemicals 60 into the production tubing 40, the treatment chemicals are released into the flow channel that communicates with surfaces on the sand screen 10 and prevent and clear particulate buildup and formation.

In another embodiment of the present invention, at least one time-release treatment chemical is coated onto a surface 70 of the sand control device 10, as shown in FIG. 2. The coating form of the treatment chemical is indicated in FIG. 2 generally by reference numeral 60′. While any effective adhesive means could be used, in a preferred embodiment, treatment chemicals are adhered to the sand control device using latex and a fatty acid material with C-18 unsaturated diamer acid mixtures, commercially known as SandWedge. Preferably, the treatment chemicals 60′ are coated onto both the inner and outer surface of each layer of the sand screen 10.

In accordance with the embodiment of FIG. 2, as hydrocarbons and drilling fluids flow through the sand control screen 10 and into the production tubing 40, the treatment chemicals 60 disposed on the surface 70 of the sand screen 10 reacts with the contaminated fluid coming into contact with the surface and thus operates to prevent the formation and buildup of unwanted particulates. In one modified version of this embodiment, the treatment chemicals are coated on the surface 70 of the sand screen 10 and then a sacrificial metal, such as zinc is applied over the layer of treatment chemicals. The zinc layer dissolves over time as the fluids pass over the surface 70, thereby exposing the layer of treatment chemicals to the fluid flow. The treatment chemicals then react with the fluids and function much in the same way as described above.

In yet another embodiment of the present invention, the sand control screen 10 is pre-packed with gravel 80, as shown in FIG. 3. In this embodiment of the present invention, the time-release treatment chemicals 60 are encapsulated and disposed within the gravel pre-pack 80. As hydrocarbons and drilling fluids flow through the pre-pack 80, the treatment chemicals 60 are released into a flow channel that communicates with the surfaces 70 on the sand control screen 10, preventing the formation and buildup of unwanted particles.

As those of ordinary skill in the art will appreciate the present invention has application in devices other than sand control screens. Indeed, the present invention also has application on or in connection with slotted liners and any other physical devices placed downhole in wells that produce formation sand along with reservoir fluids.

Therefore, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those that are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims. 

1. A method of preventing contamination of a downhole device adapted to be placed inside a wellbore, comprising the step of: placing at least one time-release treatment chemical in a flow channel that communicates with the downhole device.
 2. The method of preventing contamination of a downhole device according to claim 1 wherein the at least one time-release treatment chemical is selected from a group consisting of one or more scale inhibitors, paraffin inhibitors, asphaltene inhibitors, enzymes and any combination thereof.
 3. The method of preventing contamination of a downhole device according to claim 2 wherein the one or more scale inhibitors is selected from a group consisting of one or more phosphates, organic esthers and any combination thereof.
 4. The method of preventing contamination of a downhole device according to claim 2 wherein the one or more parrafin inhibitors is selected from a group consisting of heavy aromatic naphtha, napthenic distillates, C-20-C-28 Olefins, Trimethylbenzene and any combination thereof.
 5. The method of preventing contamination of a downhole device according to claim 2 wherein the one or more asphaltene inhibitors comprises Targon.
 6. The method of preventing contamination of a downhole device according to claim 1 wherein the at least one time-release treatment chemical is encapsulated.
 7. The method of preventing contamination of a downhole device according to claim 6 wherein the at least one time-release treatment chemical capsule is approximately 1 to 5 millimeters in diameter.
 8. The method of preventing contamination of a downhole device according to claim 1 wherein the downhole device is selected from a group consisting of gravel packs, pre-packed screens, and all-metal screens.
 9. A method of preventing contamination of a sand control device adapted to be placed inside of a wellbore, comprising the step of: disposing at least one time-release treatment chemical within, or adhering it to, a surface of the sand control device.
 10. The method of preventing contamination of a sand control device according to claim 9 wherein the at least one time-release treatment chemical is selected from a group consisting of one or more scale inhibitors, paraffin inhibitors, asphaltene inhibitors, enzymes and any combination thereof.
 11. The method of preventing contamination of a sand control device according to claim 10 wherein the one or more scale inhibitors is selected from a group consisting of one or more phosphates, organic esthers and any combination thereof.
 12. The method of preventing contamination of a sand control device according to claim 10 wherein the one or more parrafin inhibitors is selected from a group consisting of one or more heavy aromatic naphtha, napthenic distillates, C-20-C-28 Olefins, Trimethylbenzene and any combination thereof.
 13. The method of preventing contamination of a sand control device according to claim 10 wherein the one or more asphaltene inhibitors comprises Targon.
 14. The method of preventing contamination of a sand control device according to claim 9 wherein the at least one time-release treatment chemical is encapsulated.
 15. The method of preventing contamination of a sand control device according to claim 14 wherein the at least one time-release treatment chemical capsule is approximately 1 to 5 millimeters in diameter.
 16. The method of preventing contamination of a sand control device according to claim 9 wherein the at least one time release treatment chemical is coated on a surface of the sand control device.
 17. The method of preventing contamination of a sand control device according to claim 16 wherein a layer of sacrificial metal is coated over the at least one time release treatment chemical.
 18. The method of preventing contamination of a sand control device according to claim 17 wherein the layer of sacrificial metal comprises zinc.
 19. The method of preventing contamination of sand control devices according to claim 9 wherein the sand control device is selected from a group consisting of gravel packs, pre-packed screens, and all-metal screens.
 20. The method of preventing contamination of sand control devices according to claim 9 wherein the at least one time-release treatment chemical is adhered to a surface of the sand control device using latex and a fatty acid material with C-18 unsaturated diamer acid mixtures.
 21. A contamination-resistant sand control device comprising: at least one time-release treatment chemical disposed within, or adhered to, a surface of the sand control device.
 22. The contamination-resistant sand control device according to claim 21 wherein the at least one time-release treatment chemical is selected from a group consisting of one or more scale inhibitors, paraffin inhibitors, asphaltene inhibitors, enzymes and any combination thereof.
 23. The contamination-resistant sand control device according to claim 22 wherein the one or more scale inhibitors is selected from a group consisting of one or more phosphates, organic esthers and any combination thereof.
 24. The contamination-resistant sand control device according to claim 22 wherein the one or more paraffin inhibitors is selected from a group consisting of one or more heavy aromatic naphtha, napthenic distillates, C-20-C-28 Olefins, Trimethylbenzene and any combination thereof.
 25. The contamination-resistant sand control device according to claim 22 wherein the one or more asphaltene inhibitors consists of Targon.
 26. The contamination-resistant sand control device according to claim 21 wherein the at least one time-release treatment chemical is encapsulated.
 27. The contamination-resistant sand control device according to claim 26 wherein the at least one time-release treatment chemical capsule is approximately 1 to 5 millimeters in diameter.
 28. The contamination-resistant sand control device according to claim 21 wherein the sand control device is selected from a group consisting of gravel packs, pre-packed screens, and all-metal screens.
 29. The contamination-resistant sand control device according to claim 21 wherein the at least one time-release treatment chemical is adhered to a surface of the sand control device using latex and a fatty acid material with C-18 unsaturated diamer acid mixtures.
 30. The contamination-resistant sand control device according to claim 21 wherein the at least one time release treatment chemical is coated on a surface of the sand control device.
 31. The contamination-resistant sand control device according to claim 30 wherein a layer of sacrificial metal is coated over the at least one time release treatment chemical.
 32. The contamination-resistant sand control device according to claim 31 wherein the layer of sacrificial metal comprises zinc. 